In the conventional communication system, the Farrow structure is usually used to process the interpolating calculation during the interference cancellation of cross clock domain, so as to transform corresponding data among different clock domains. In the art, the Farrow structure is a polynomial-based interpolation filter which can alleviate the complexity of the interpolating calculation. However, the application of the polynomial approximation would lead to an inevitable computational errors or bias. In general the maximum computational error will appear when the phase angle is at 180 degrees. Also, as the clocks of input and output data get closed to each other, the Farrow structure would have a downgrading performance and the computational error would rise up. In particular, when the two clocks are almost the same for the input and output data, a correcting computation to obtain interpolated data having 180-degree phases is extremely impossible from a Farrow-structure scheme.
For example, in the application of HDMI Ethernet channel, due to the feature of bi-direction transmission in a single cable, interference may arise from the incoming signals and the echo of the outgoing signals. In the art, an echo canceller is usually introduced to perform the cancellation of the echoes. Because a small clock difference of less than about 200 ppm may exist between the opposing ends of the HDMI Ethernet channel, the data at the local transmitter end needs to undergo clock domain switching to transform its clock domain into that of the data at the local receiver end, and then the echo canceller can be applied to depress the possible echoes according to the clock domain of the receiver end. Here, if the Farrow structure is introduced to process the clock domain switching, the interpolating accuracy would be poor due to the clock difference between the transmitter end and the receiver end. Thus, to obtain a satisfied computational precision from the Farrow structuring, a high-order polynomial is inevitable, but trade-off is a large number of taps in the Farrow structure. As a result, the computational complexity is high and the time delay in signaling is usually prolonged.
In a network apparatus with multiple communication ports, one port is often interfered by the other one. For example, to reduce the production cost, a transformer of a multi-port switch often has coils of two or four ports wrapped together in the same element. The internal coils of the transformer make signals interfere with each other, and this would downgrade signaling performance due to interference between the neighboring ports. Therefore, it is in need to develop a new technique to eliminate the cross-clock-domain interference between different communication ports in a network apparatus.